JP2988936B2 - 3D graphics processing unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention displays three-dimensional graphic information (referred to as graphics including graphics and images in this specification) on a two-dimensional plane in a form that is easy for humans to understand. The present invention relates to a three-dimensional figure processing device.

2. Description of the Related Art When displaying a three-dimensional figure on a two-dimensional plane such as the display surface of a cathode ray tube display, the figure is displayed with shading or hidden surface (line) removal (hidden surface elimination) is performed. Is displayed in an easy-to-understand format.

FIG. 6 is a block diagram showing an example of a conventional apparatus, in which (1) is a graphic processor (hereinafter abbreviated as GPU), (2) is a graphic database, and (4) is a frame buffer (abbreviated as FB). ) And (5) are display devices (hereinafter abbreviated as CRT), and (60) is a Z buffer.

The graphic data to be displayed on the CRT (5) is stored in the graphic database (2). For example, one polygon (in this case, a polygon on one plane in three dimensions) is converted to a CRT
When displayed on (5), the coordinate position of each vertex of the polygon (XYZ with the direction perpendicular to the display surface of CRT (5) as the Z axis)
Stored are coordinates (coordinate positions related to rectangular coordinates) and the luminance at which the polygon is to be displayed (B value, where the B value in this specification includes color information for color display). GPU
In (1), data of such a shape is input from the graphic database (2), and this polygon is displayed on the CRT (5) in a raster scan manner (more precisely, the projection of this polygon on the XY plane). Generate B value and FB
Write to (4). Each pixel (pixel,
The B value is written using the XY coordinate position of the smallest unit pixel) as an address. For example, if the B value inside the polygon is B1
(Eg, green), if the external B value is 0 (black), B1 is written at the XY coordinate position inside the polygon, 0 is written at the XY coordinate position outside the polygon, and the CRT (5) is green. The filled polygon is displayed.

To display hidden surface removal, the GPU (1) executes writing to the FB (4) with reference to the data in the Z buffer (60). The Z buffer (60) stores a Z value using the XY coordinate position as an address. The GPU (1) calculates a Z value corresponding to the XY coordinates of the polygon and compares it with the Z value of the same XY point in the Z buffer. If the latter is smaller (however, a left-handed coordinate system is assumed. ), Which means that this part of the polygon must not be displayed on the CRT (5), since that means that this part of the polygon is already hidden by other graphic parts already stored in FB (4). Is shown. Only when the Z value in the polygon is smaller than the Z value in the Z buffer (60) in the comparison of the Z value, the B value of that polygon is written to the FB (4), and the Z value of the polygon is written in the Z buffer ( Write to 60).

 The hidden surface removal display can be performed by the above processing.

[Problems to be Solved by the Invention] The conventional devices as described above have various problems as described below. That is, (a) The contents of FB (4) are updated every frame, and the data of the previous frame cannot be used. For example, when it is desired to display a graphic that moves in front of a fixed background graphic, the GPU (1) must perform a fixed graphic generation process and a motion graphic generation process each time, which requires a long time.

(B) When an instruction is given from the CRT display surface using a pointing device and only the indicated graphic is to be picked, a long time is required for the processing.

(C) As shown in FIG. 6, the flow of information is one-way from GPU to FB to CRT, so there is a problem that the function as a man-machine interface is lacking.

The problem to be solved by the present invention is to obtain a three-dimensional graphic processing apparatus free from the above-mentioned problems.

[Means for Solving the Problems] In the present invention, the Z buffer is extended to form an extended Z buffer (hereinafter, the extended Z buffer is abbreviated as VF), and in addition to the Z value, the N value (the hue / name information is represented by the N value) Or an N-value and a B-value, and an interference calculator (hereinafter abbreviated as IPU) for controlling the writing to the VF and the FB is provided.

[Operation] Various controls are possible in writing to FB and VF by IPU and read data from VF, and IP
U can interrupt the upper processor and function as a man-machine interface.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, in which the same reference numerals as in FIG. 6 denote the same or corresponding parts,
(3) is an IPU (interference arithmetic unit), and (6) is a VF (extended Z buffer). FIG. 2 is an explanatory diagram showing an example of the VF (6) in FIG. 1. In the example shown in FIG. 2, the addresses corresponding to the XY coordinate points are 2048 addresses for the X address and 1024 addresses for the Y address. Is written with a 16-bit Z value, and 16 bits are allocated to the N value and the B value according to the purpose of use. In some cases, the number of bits assigned to the B value is 0 (that is, the B value is not stored).

FIG. 3 is a block diagram showing an example of the IPU (3) in FIG. 1. In FIG. 3, the same reference numerals as those in FIG. 1 denote the same parts, (31) is a comparison control unit, (32) is a mask control unit, and (33). ) Is a look-up table (hereinafter abbreviated as LUT). The mask control unit (32) has a mask memory (not shown). The mask memory stores addresses to prohibit writing to VF (6) and FB (4). When the XY coordinates of the transmitted pixel match the address of the mask memory, the mask control unit (32) sets the VF regardless of the result of the comparison in the comparison control unit (31).
Writing to (6) and FB (4) is prohibited. LUT (3
3) Write N value and B value sent from GPU (1) or upper processor via GPU (1) to FB (4).
This is a conversion table for converting into a value, and is composed of, for example, a RAM.

FIG. 4 is a block diagram showing an example of the comparison control unit 31 of the IPU (3) in FIG. 1. In FIG. 4, the same reference numerals as those in FIG. 1 denote the same parts, (35) is a Z register, and (36) is N register. An arbitrary Z value Zi can be set in the Z register (35), and an arbitrary N value Ni can be set in the N register (36).
The Z value and N value input from the GPU (1) are Zd and Nd, respectively.
Assuming that the Z value and N value read from the VF (6) are Zv and Nv, respectively, the IPU (3) can perform various controls based on the relation of, for example, Zd-Zi-Zv.

FIG. 5 shows an IPU (3) having the comparison control unit 31 shown in FIG.
In the figure, the hollow cylinder shown in (a) is a figure generated by the GPU (1), and (b) is a Z register (3
The Z value (referred to as Zi) stored in 5). The condition where the Z value is constant is a plane perpendicular to the Z axis. (C) is a figure written in VF (6). Of Zd of hollow cylinder (a),
If the part of Zd> Zi and the graphic (c) are displayed by the hidden surface removal method, the graphic (d) is obtained, and this is written in the VF (6) and the FB (4) and displayed on the CRT (5). Can be done. If the figure of VF (6) is as shown in (e), VF (6), FB
The figure written in (4) is as shown in (f).

The IPU (3) also has a function of interrupting the GPU (1) or a higher-order processor based on the result of the comparison. For example, in the configuration of FIG. 4, Zd = Zv, Nv = Ni, Zd
= Zv and Nv = Ni can be freely set as the interrupt condition for the GPU (1). Furthermore, IPU (3)
When writing the N value and B value of VF (6) as the B value of FB (4), an offset value can be specified for the XY value of the writing location of FB (4).

 Hereinafter, application examples of the present invention will be described.

(I). In the case of displaying animated figures, when displaying a figure moving in front of a stationary background figure, the background figure is first written in both FB (4) and VF (6). Next, the first figure of the moving figure is written into the FB (4) while comparing it with the contents of the VF (6). In this case, writing to the VF (6) is not performed, and the background figure is left as it is in the VF (6). Next, while comparing the second figure of the moving figure with the contents of VF (4)
Write to FB (4). At this time, in the pixel where the first figure exists and the second figure does not exist, the background figure stored in VF (6) as a result of the comparison between the second figure and VF (6) is The first figure written to FB (4) is erased. In this way, it is possible to display a figure moving in front of a still background with a simple process.

(B). In the field of graphic processing, it is often used in man-machine communication that an operator designates a figure displayed on a CRT (5) with a pointing device so that a machine recognizes which figure is indicated. It is called a pick etc.
By writing the N value in VF (6), VF (6) can be read out using the XY coordinates specified by the pointing device as an address, and the N value of the figure can be immediately known.

(Is). Inspection of whether or not a figure represented in three dimensions interferes with a figure is an inspection required in CAD (computer aided design). Conventional equipment required a large amount of data processing for this inspection.
By using (6) and IPU (3), an interrupt can be issued to the host processor according to the comparison result of IPU (3), so that high-speed processing can be performed with a relatively small amount of data processing. For example, when the robot's arm moves to various positions, does it collide with other parts of the robot itself,
A real-time simulation for inspecting for interference with other objects can be performed by the apparatus of the present invention.

[Effects of the Invention] As described above, according to the present invention, the Z-buffer is expanded, and by adding a simple circuit of providing a dedicated processor (IPU) for these processes, various processings for three-dimensional graphics can be performed. An effective processing method can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an example of a VF (extended Z buffer) in FIG.
FIGS. 3 and 4 show the IPU (interference calculator) of FIG. 1, respectively.
FIG. 5 is an explanatory diagram showing an application example of the IPU shown in FIG. 4, and FIG. 6 is a block diagram showing an example of a conventional device. (1) GPU (graphic processor), (2) graphic database, (3) IPU (interference calculator), (4) F
B (frame buffer), (5) CRT (display device),
(6) is a VF (extended Z buffer), (32) is a mask control unit, (33) is an LUT (lookup table), (35) is a Z register, and (36) is an N register. In the drawings, the same reference numerals indicate the same parts.

Claims (5)

(57) [Claims] 1. A graphic database for storing graphic data, and XYZ orthogonal coordinates having a direction perpendicular to a display surface of a display device as a Z axis based on the graphic data read from the graphic database. And is called a figure)
XY for each pixel (minimum unit pixel)
A graphic processor that determines the Z value (hereinafter referred to as Z value) and luminance information (hereinafter referred to as B value) of the coordinate point, a Z buffer that stores the Z value using the information of the XY coordinate point as an address, and information of the XY coordinate point And the Z value determined by the graphic processor is compared with the Z value at the same XY coordinate position in the Z buffer, and the contents of the Z buffer and the frame buffer are determined according to the comparison result. And a means for displaying the contents of the frame buffer on a display device, the hue / name information (hereinafter referred to as N value) in addition to the Z value of the Z buffer, or An extended Z-buffer that also stores N and B values, inserted between the graphics processor and the frame buffer; And outputs the B value of the frame buffer, the Z value and the N value of the extended Z buffer, and the B value according to the result of the processing with reference to the contents of the extended Z buffer. A three-dimensional figure processing device, comprising: an interference calculator for interrupting. 2. An interference calculator comprising a Z register and an N register capable of setting an arbitrary Z value and an arbitrary N value, wherein the contents of the Z register and the contents of the N register are stored in the graphic processor. 3. The three-dimensional figure processing apparatus according to claim 1, wherein the data is referred to when processing data from a computer. 3. The interference calculator includes means for writing the contents of the N value and the B value of the designated XY coordinate point of the extended Z buffer into the frame buffer of the XY coordinate point to which the designated offset has been added. 3. The three-dimensional figure processing apparatus according to claim 2, wherein: 4. The interference calculator includes a mask memory for storing an address prohibiting writing to the frame buffer and the extended Z buffer, and stores the address in the frame buffer and the extended Z buffer in accordance with the contents of the mask memory. 4. The three-dimensional graphic processing apparatus according to claim 1, wherein writing is prohibited. 5. The look-up processor for converting an N value and a B value input from the graphic processor or a higher-order processor via the graphic processor into a B value to be written into the frame buffer.
5. The three-dimensional graphic processing apparatus according to claim 1, further comprising a table.